This invention relates to foam producing and dispensing apparatus and more particularly, it concerns an improved cap assembly attachable to the mouth of a collapsible bottle containing foamable liquid and air and by which the foam producing and dispensing operation of such apparatus is materially enhanced.
In U.S. Pat. No. 3,709,437 issued Jan. 9, 1973 to H. E. Wright, there is disclosed a method and apparatus for producing and dispensing foam in which a collapsible reservoir or bottle containing foamable liquid and air is fitted with a cap assembly supporting within the bottle mouth a mixing chamber having air inlet passages elevated above the liquid in the bottle and having a check valve controlled inlet in communication with a dip tube depending below the level of foamable liquid in the bottle. The mixing chamber opens at its upper end through a porous homogenizing element to a dispensing outlet carried by the cap. The device operates such that upon collapsing deformation of the bottle, both foamable liquid and air within the bottle are forced into the mixing chamber to produce foam which is passed directly to the discharge passage.
Foam producing and dispensing devices of the type disclosed in the aforementioned U.S. patent have proven highly effective in the instantaneous generation and dispensing of a highly consistent and relatively dry foam. Some difficulty has been evidenced, however, in achieving a rapid return of air back into the bottle as required for repeated foam generation and dispensing cycles. In the prior devices, the return of air to the interior of the bottle after a dispensing operation was directly through the passages by which air was introduced from the bottle interior into the mixing chamber. Inasmuch as the upper region of the chamber and discharge passage are filled with foam during this phase of the operation, the residual foam in the discharge port and the homogenizing element restrict the return of air into the bottle upon restoration thereof to its original configuration.
Although the restriction presented by the homogenizing element is circumvented in at least one embodiment disclosed in the aforementioned patent by allowing the homogenizing element to be advanced upwardly against the peripheral seal during the discharge of foam from the device and to drop inwardly to a position in which air flow about the homogenizing element is permitted, the restriction represented by residual foam in the discharge nozzle is not in any way accounted for. In addition, the provision for floating movement of the homogenizing element represents an increment of increased manufacturing costs in the device.